Apparatus for use in wire or radio communications.



.L. DE FOREST.

APPARATUS FOR use IN WIRE 0R RADIO COMMUNICATIONS.

APPLICATION FILED APR-9.1915.

Patented Apr. 3, 1917.

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AIPIEAT'US EOllt USE Ill QE EMIU TCATTONS.

Specification of Eettcra Eatent.

Patented new. a, rear.

Application filled April Q, 1915. Serial lilo. $43,172.

This invention relates to apparatus for use p in wire or radio communications. The ob ect of the invention is to provide an apparatus and wiring circuits therefor,

which is simple and eficient for use in. wire or radio commun1cat1ons. w

A. further ob ect of the invention is to provide means for detecting minute changes in potential of electric currents. 3

Other objects of the invention will appear more fully hereinafter.

The invention consists substantially in the econstruction, combination, location, and various circuit arrangements all as will be more fully hereinafter set forth, as shown in the accompanying drawing, and finally pointed out in the appended claims.

Referring to the drawing,-

Figure 1 is a circuit diagram showing one arrangement of-circuits for accomplishing the objects of my invention, as applied to wire or radio communications.

Figs. 2, 3, and 4:, are similar views show ing modified circuit diagrams, andembodying my invention.

The same part is designated by the same reference numeral wherever it occurs throughout the several views.

It is among the special purposes of my present invention to provide apparatus for use in signaling by radio means or over wire or cable lines for producing or controlling audible sounds in accordance with the signals received, and for use, particularly with exceedinglyweak received signal impulses such as those received, for example, over long-telegraph wires or long submarine cables.

T propose to control, by means of received signal impulses, the pitch of sounds locally created at the receiving station which are due to interference between two or more sources of continuous oscillations, or alternating currents, or, in other words, the pitch of a beat note thus produced.

In Fig. l T have shown my invention as applied to a wire or cable communication system wherein l employ oscillating audions of the usual type, and oscillating systems associated with each audion either inductively or otherwise whereby the oscillations produced in one system are interfered with by the induced oscillations produced in the other oscillating system so that the beat or interference currents are set up in each circuit and may be readily-detected by means of a telephone receiver, or other detecting device located in each circuit.

Reference numeral 1 generally designates the end of an incoming lead, such as from a radio, antenna earth system, but which is shown in Fig. l as an incoming line or cable. If desired, a blocking capacity such as a condenser 2 may be inserted in the incoming line, as shown, and the line is connected to the grid or input electrode 6 of audion 3. The two plate electrodes 5, 5, of the audion bulb 3 are connected together and in series with a telephone receiver, or other selecting device indicated at 24, and to the positive terminal of a current source, which is shown in this instance as a battery 22, and finally to one end of the filament 8 of the audion in the usual and well known manner. The filament is heated from the current source indiping condenser 12 to an oscillating circuit made up of the variable condenser 14 bri dg ing the inductance 15 which is connected by its other terminal to the circuit including the telephone receiver or other detecting device hereinbefore described. Inductively associated with the coil 15 is a coil 16 of a second oscillating circuit one terminal of which is connected through a stopping condenser 13 to the grid electrodes 10, 10 of a second oscillating audion d, and the variable capacity, such as a condenser 17, bridging the coil 16. The plate electrodes 9, 9 of audion l, are likewise connected in parallel, and through a second telephone receiver or like impedance 25 to the positive terminal of a source of ourrent, such, for example, as a battery-23, and

"of the second audion 4 is connected to the plate or wing electrode 9.

By ,means of the arrangement just described, wherein two oscillating audion circuits are associated with each other, if both of the circuits are arranged to generate os- 'cillations of say 300,000 and 300,300 periods per second, respectively, a pure beat note having a frequency of 300 periods per second will be heard or detected at either detecter or telephone receiver. 24 or 25. The

slightest disturbance of the normal conditions of one of these oscillating audions will affect the period of its oscillations to a slight degree, thus, since in the arrangement shown the period of oscillation depends not only upon the capacity and inductance constants of the associated circuits, but also on the.

temperature of the filament, the potential of the battery 22 applied across the. space between plates 5 and filament 8, and also on the potential at any moment impressed on the grid electrode 6, it therefore follows that when an electric charge or changes of potential from the incoming line or cable 1 is impressed upon the grid electrode 6, the audion 3 will oscillate at a slightly different frequency, either greater or less than normal. If this change in frequency is very small, say only 30 periods per second, or

- equal to approximately one hundredth part of one'per cent, the car, when an ear re ceiver is employed, pan readily detect the change in pitch of the beat note thus efi'ected.

It will be seen therefore, that I have supplied an extraordinarily sensitive means for detecting exceedingly minute changes in potential, and it is evident that with but little training, a skilled Morse operator is enabled to detect faint signals produced simply by periodic changes in the pitchL of an otherwise constant pitch note, when my invention is applied either to radio or wire telegraphy.

In Fig. 2-1 have shown a modification of the arrangement shown in Fig. 1. In this arrangement only one double oscillating audion is employed. The input electrode 6 is connected to one side of the incoming line, as hereinbefore described, through the capacity 2, and the other side of the incoming line, 31, is here shown as connected to the filament 8 of the audion. In this instance, the oscillating circuits includin the stopping condensers 12, 13, and the inductances 15, 16, and capacities 17, 14, respectively, are respectively connected across the grid electrode 6 and the plate electrode 9, and the limited thereto.

plate electrode 5 and grid electrode 7. Each of the plate electrodes 5, 9 is connected to the filament 8 through separate current sources, whichare shown, for example, as batteries 22 and 23 respectively, and through the detectors such as telephone receivers or other suitable impedances 25, 24.

The results obtained by this arrangement are identical with those'obtained by the arrangement shown in Fig. 1. Continuous oscillations are generated by each of the two circuits, which are loosely coupled and inductively associated with each other. The incoming signal charges or impulses delivcred to the input electrode 6 distort the oscillating condition and period of one of these circuits to a greater degree than it does the other, and thereby produces a change in the beat note pitch, as hereinbeforc described.

In Fig. 3 I show an arrangement similar to Fig. 2 wherein the incoming line leads terminate in the primary winding of a transformer 26 which is preferably wound to step-up the voltage, and having one secondary coil terminal connected to the grid electrode 6 and the other terminal thereof connected to the grid electrode 7. Stopping condensers 2 and 2' may be inserted in these respective circuit connections, but they are not necessary, and my invention is not to be From the center or neutral point of the secondary winding of the transformer 26, I propose, in this instance, to

connect a lead 27 to the filament heating circuit .of the audion 3. If desired, and as shown, a current source, such as a battery 35,

may be inserted in the lead 27 with its negative terminal connected to the neutral point of the transformer secondary coil so that if the stopping condensers 2, 2, are omitted, the grid electrodes 6 and 7 of the audion 3 will be negatively charged, and the sensitiveness of the device thereby increased.

With the arrangement shown in Fig. 3, a positive charge is impressed on one of the grid electrodes while a negative charge is impressed on-the other grid electrode, thereby loading one of the two local oscillating circuits and decreasing the load on the other thereby increasing the difference in ratio of vibration of the two circuits and altering the pitch of the beat note.

In Fig. 4 I show another method of altering the pitch of the beat note by means of the incoming signal impulse, wherein the incoming line 1 is led to earth or ground or the return conductor through the coil of a direct current galvanolneter 29. This coil carries a long light conducting arm 40 carrying at its extreme end a small, light, movable plate or disk 32, preferably of thin aluminum leaf. In close proximity to this movable plate or disk is positioned a stationary or fixed'plate 33, the two plates 32 and 33 formmantra .ing armatures of a small condenser connected in parallel to a small variable con- 15, 17, which is connected as hereinbefore described between the two electrodes 5 and 6 of an oscillating audion 3. The two electrodes 7 and 9 are here shown as being connected to asecond oscillatin circuit includin the inductance '16 briged by the variab e capacity it, llhe audion circuits are the same as 'hereinbefore described in connection with other views of the drawing.

lin the arrangement above described, the incoming signal impulse, by moving the movable armature 32 relative to the fixed armature 33 changes the capacity or the oscillating circuit to which galvanometer 29 is connected, and thereby alters the pitch of the beat note as heard in either of the telephone receivers or detectors 24: or 25 as hereinbefore described.

lln all of the arrangements described, the condensers in the oscillating circuits, designated at 14 and 17 are preferably made variable for the purpose of adjusting theperiods ofthe oscillating circuitsot which they form a part Thus an operator can vary the normal pitch of the beat note, making it high or low to suit his'desire, or necessity. By var ing-the degree ofcoupling between the coils l5 and it, or by varying the degree of heat of the filament of the audion, regulation can also be obtained of the intensity of the beat notes or received signals:

ile l have shown the incoming line 1 throughout the several views as being a telegraph line or cable, it will be readily understood that I am not to be limited thereto, as my invention, in its broad sco e as defined in the claims, may be also as e ciently used in connection with an aerial conductor and ground lead, and whereas I have shown various arrangements for accomplishing the objects and purposes of my invention, many changes may occur to those skilled in the art without departing from the broad scope of my invention. at I claim as new and useful, and of my own invention, and desire to secure by Letters Patent, is,-

1., In a receiving system a normally oscillating audion, oscillating circuits associated therewith and connected between the cold .electrodes thereof, and means controlled-by of oscillation of one of said oscillating circuits and means for detecting said alteration of period.

3. In -a receiving system an oscillation generator, a plurality of oscillating circuits denser 17 of the local oscillating circuit associated therewith and connected between the cold electrodes thereof, and means controlled by the receivcd impulses for altering the period of oscillation of said oscillating circuits.

d. lln a receiving system an oscillation generator, a plurality of oscillating circuits associated therewith and connected between the cold electrodes thereof, means controlled by the received impulses for altering the period of oscillation ofsaid oscillating circuits and means for detecting saidperiod alteration.

5. in a receiving system, a normally oscillating audion, osclllating circuits associated therewith and connected between the cold electrodes thereof, and means controlled by the received impulses for altering the period of oscillation of one of said osclllating circuits and a detecting circuit associated with said audion. a

6. lln a receiving system an oscillating audion, oscillating circuits associated therewith 'and connected between the cold electrodes thereof, and means controlled by the received impulses for altering the period of oscillation ofone of said osclllating circuits and a detecting circuit associated with said 'audion, means for setting up beat currents in said detecting circuit, and a signal indicating device included in said detecting circuit,

'3. A plurality. of oscillation generators each having a diderent period and associated with each other, a receiving circuit therefor, and means controlled by the received signals for producing changes in pesaid audions, means for producing changes,

in periodicity in the oscillating circuit of one of said oscillating audions in accordance with received signals and means associated with each of said oscillating audions for detecting said changes in periodicity.

10. In a signal receiving system, two audions, oscillating circuits connected across the cold electrodes of each of said audions, and inductively associatin said audions to each other, means for pro ucing changes in periodicity in one of said oscillating circuits in accordance with received signals, and

means associated with each of said oscillating circuits for detecting said changes in periodicity. c

11. in a detector system, a plurality of oscillating circuits, means for generating set up by said interferences.

12. In a detector system, a plurality of oscillating circuits, means for generating alternating currents in each of said oscillating circuits, means for setting'up interferences between the alternating currents generated in each of said oscillating circuits,

and means controlled by the received intpulses to control the pitch of the beat note set "up by said interferences and means to detect said beat note. v

13. In a detector system, a plurality of oscillating circuits, means for generating alternating currents in each of said oscillating circuits, means for setting up interferences between the alternating currents generated in each of said oscillating cir' cuits, and means controlled by the received impulses to control the pitch of the beat note set up by said interferences, and mea as associated with each of said oscillating circuit's for detecting said heat note.

In testimony whereof I have hereunto so my hand on this 7th day of April A. 1).,1915. LEE on FOREST 

